1. Field of the Invention
The present invention relates to a backlight unit, and more particularly, to a backlight unit and a liquid crystal display (LCD) device using the same, which are manufactured in a slim type.
2. Discussion of the Related Art
Flat Panel Display (FPD) devices are applied to various electronic products such as portable phones, tablet PCs, notebooks, etc. The FPD devices include Liquid crystal Display (LCD) device, Plasma Display panels (PDPs), and Organic Light Emitting Display (OLED) Device, etc. Recently, elctropohretic display (EPD) devices are widely used as the FPD devices.
In such FPD devices (hereinafter simply referred to as a display device), the LCD devices are being the most widely commercialized at present because the LCD devices are easily manufactured due to the advance of manufacturing technology and realize a drivability of a driver and a high-quality image.
Since the LCD devices are not self-emitting devices, the LCD devices include a backlight unit provided under a liquid crystal panel, and display an image by using light emitted from the backlight unit.
The LCD devices are categorized into an edge type and a direct type depending on an arrangement of a light source configuring the backlight unit.
FIGS. 1A and 1B are side views illustrating a configuration of a light source and a light guide panel applied to a related art edge type LCD device. FIG. 1 (a) illustrates a light guide panel 13 having the same width as that of a light source 12, and FIG. 1 (b) illustrates a light guide panel 14 having a smaller width than that of the light source 12.
In the edge type LCD device, as illustrated in FIGS. 1A and 1B, a light source unit including a printed circuit board (PCB) 11 and the light source 12 is disposed at one side of the light guide panel 13 (14) which is provided at a rear surface of a liquid crystal panel. A light emitting diode (LED) package equipped with an LED is being widely used as the light source 12.
Light emitted from the light source 12 is converted into flat light by the light guide panel 23, and is irradiated onto the liquid crystal panel.
Therefore, in comparison with a direct type LCD device, the edge type LCD device is reduced in thickness.
In the related art edge type LCD device, as illustrated in FIG. 1A, a thickness X of the light guide panel 13 is formed identically to a width Y of the light source 12 in consideration of light incident efficiency. In detail, the width Y of the light source 12 denotes a width of a window in which light is emitted from the LED package configured with the LED.
As described above, since the thickness X of the light guide panel 13 is formed identically to the width Y of the light source 12, most of light emitted from the light source 12 is incident on the inside of the light guide panel 13 through a side of the light guide panel 13. Therefore, a light incident efficiency of the light source 12 is high.
However, since the thickness X of the light guide panel 13 is formed identically to the width Y of the light source 12, it is difficult to manufacture a slim LECD device.
In order to manufacture a slim LCD device, as illustrated in FIG. 1B, a method that reduces a thickness X′ of the light guide panel 14 compared to a width Y′ of the light source 12 has been proposed.
However, if the thickness X′ of the light guide panel 14 is reduced, as illustrated in FIG. 1B, an amount of light which is not incident on a side of the light guide panel 14 in light emitted from the light source 12 increases. That is, the light incident efficiency of the light source 12 is reduced.
Therefore, a method that slims an LCD device by reducing the thickness X′ of the light guide panel 14 has a limitation.
That is, in the related art LCD device, there is a limitation in slimming an LCD device without a reduction in light incident efficiency.